The Bank of New Zealand is the first New Zealand bank to become carbon neutral.

Three years ago, the bank set a target of reaching the environmental milestone by 30 September 2010 - it actually reached it three months early in July.

It's achieved carbon neutrality by reducing emissions through greater energy and vehicle efficiency, encouraging changed behaviour by employees at work and at home, and through offsetting unavoidable emissions by purchasing quality carbon assets.

The bank now occupies three 5-star green rated corporate buildings.

The move follows a similar carbon neutral commitment by its Australia parent, the National Australia Bank.